Microfabricated devices are used in a wide variety of industries, ranging from the integrated circuits and microprocessors of the electronics industry to, in more recent applications, microfluidic devices and systems used in the pharmaceutical, chemical and biotechnology industries.
Because of the extreme small scale of these devices, as well as the highly precise nature of the operations which they perform, the manufacturing of these microfabricated devices requires extremely high levels of precision in all aspects of fabrication, in order to accurately and reliably produce the various microscale features of the devices.
In a number of these disciplines, the manufacturing of these microfabricated devices requires the layering or laminating of two or more layers of substrates, in order to produce the ultimate device. For example, in microfluidic devices, the microfluidic elements of the device are typically produced by etching or otherwise fabricating features into the surface of a first substrate. A second substrate is then laminated or bonded to the surface of the first to seal these features and provide the fluidic elements of the device, e.g., the fluid passages, chambers and the like.
While a number of bonding techniques are routinely utilized in mating or laminating multiple substrates together, these methods all suffer from a number of deficiencies. For example, silica-based substrates are often bonded together using thermal bonding techniques. However, in these thermal bonding methods, substrate yields can often be extremely low, as a result of uneven mating or inadequate contact between the substrate layers prior to the thermal bonding process. Similarly, in bonding semi-malleable substrates, variations in the contact between substrate layers, e.g., resulting from uneven application of pressure to the substrates, may adversely affect the dimensions of the features within the interior portion of the device, e.g., flattening channels of a microfluidic device, as well as their integrity.
Due to the cost of substrate material, and the more precise requirements for microfabricated devices generally, and microfluidic devices, specifically, it would generally be desirable to provide an improved method of manufacturing such devices to achieve improved product yields, and enhanced manufacturing precision. The present invention meets these and a variety of other needs.
The present invention is generally directed to improved methods of manufacturing microfabricated devices, and particularly, microfluidic devices. In particular, in a first aspect, the present invention provides methods and apparatuses for bonding microfabricated substrates together. In accordance with the methods of the present invention, a first substrate is provided which has at least a first planar surface, a second surface opposite the planar surface, and a plurality of apertures disposed through the first substrate from the first surface to the second surface. A vacuum is applied to the apertures, while the first planar surface of the first substrate is mated with a first planar surface of the second substrate. The mating of these substrates is carried out under conditions wherein the first surface of the first substrate is bonded to the first surface of the second substrate. Such conditions can include, e.g., heating the substrates, or applying an adhesive to one of the planar surfaces of the first or second substrate.
In a related aspect, the present invention also provides an apparatus for manufacturing microfluidic devices in accordance with the methods described above. Specifically, such apparatus typically comprises a platform surface for holding a first substrate, the first substrate having at least a first planar surface and a plurality of holes disposed therethrough, and wherein the platform surface comprises a vacuum port connected to a vacuum source, for applying a vacuum to the plurality of holes. The apparatus also comprises a bonding system for bonding the first surface of the first substrate to a first surface of a second substrate.